1. Field of the Invention
This invention relates to a system and apparatus for restraining lateral movement of metal plates and sheet and the like while they are being conveyed longitudinally through various stations as their edges are worked upon. Examples of such operations are edge trimming and forming of plates prior to shaping into large diameter pipe, or in welding reenforcing elements thereon, or performing other fabricating operations wherein skewing or misalignment of the plate may occur and would be undesirable and detrimental to subsequent operations.
2. Description of Prior Art
It is well known to use clamping or gripping means on the trailing edges of metal sheet and plate to restrain lateral movement of a flat section as it is passed through a metal working operation. In such arrangements the gripping elements may be positioned within channels or other guiding arrangements to permit forward and reverse movement of the clamps and plates, and at the same time to prevent lateral movement thereof. These systems have not always been satisfactory because of the difficulty of maintaining adequate gripping pressure while the plate section moves forward and maintaining it in the proper position, or otherwise controlling the plates and clamps, while they are subjected to the tensions and side forces present during fabrication of the plate or any other working operation. Further, the various types of apparatus presently in use are expensive and complicated to operate.
U.S. Pat. No. 4,015,702 is to a method and apparatus for successively conveying large metal plates of varying sizes to a particular position where a welding operation of the like may be performed. It utilizes a guide beam in which gripping elements are used on the forward and rear edges of each plate section. However, the gripping elements are intended to be fastened to channel beam guides and the channel beams travel through the work area. Moreover, the channel beams are moved by a rack and pinion arrangement which is cumbersome and far too slow to be practical for an operation involving edge forming and trimming of a plate for use in making large diameter pipe.
U.S. Pat. No. 4,090,703 discloses apparatus for feeding rectangular metal sheets to a cupping press in which can body blanks are cut and drawn from the metal sheets. Several sheets feeding mechanisms are provided along a conveyor table. Endless chains and feedfinger arrangements move the metal sheets. The trailing edge of the sheet is engaged by a reciprocating feedfinger arrangement to advance and accurately position a sheet section from which blanks are to be stamped. The scrap is discharged froom the press or table on which the stamping takes place. A plurality of longitudinally extending laterally narrow strips are provided to support the sheet sections which are to be blanked. There are also three separate feed units. The metal sections are not subjected to the lateral forces and torque comparable to roll forming or other fabricating operations which would cause misalignment and skewing during passage through the machine.
U.S. Pat. No. 1,986,857 discloses a complicated machine for folding corrugated paper blanks during their passage across an operating table. Although chain and pulley arrangements are disclosed, the nature of the materials which are being worked upon, that is, corrugated paper, and the problems involved are different than those encountered by applicant. The equipment employed in the patent is primarily a feeding device and would not be useful for handling steel plate.
Accordingly, the art does not suggest a simple, low cost and efficient arrangement such as the present invention.